[PATCH V6 41/49] x86/nmi: Use C entry code

[Lai Jiangshan <jiangshanlai@gmail.com>]

From: Lai Jiangshan <laijs@linux.alibaba.com>

Use DEFINE_IDTENTRY_IST_ENTRY to emit C entry function and use the function
directly in entry_64.S.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
 arch/x86/entry/entry_64.S       | 17 ++---------------
 arch/x86/include/asm/idtentry.h |  5 ++++-
 arch/x86/kernel/Makefile        |  1 +
 3 files changed, 7 insertions(+), 16 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index ac05cbf894f5..cc552e23d691 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1306,21 +1306,8 @@ end_repeat_nmi:
 	PUSH_AND_CLEAR_REGS
 	ENCODE_FRAME_POINTER
 
-	/*
-	 * Use paranoid_entry to handle SWAPGS and CR3.
-	 */
-	call	paranoid_entry
-	UNWIND_HINT_REGS
-
-	movq	%rsp, %rdi
-	movq	$-1, %rsi
-	call	exc_nmi
-
-	/*
-	 * Use paranoid_exit to handle SWAPGS and CR3, but no need to use
-	 * restore_regs_and_return_to_kernel as we must handle nested NMI.
-	 */
-	call	paranoid_exit
+	movq	%rsp, %rdi		/* pt_regs pointer */
+	call	ist_exc_nmi
 
 	POP_REGS
 
diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
index 737fbbe19d84..b65cb61aafdc 100644
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -372,6 +372,8 @@ __visible __entry_text void ist_##func(struct pt_regs *regs)		\
 #define DEFINE_IDTENTRY_NOIST(func)					\
 	DEFINE_IDTENTRY_RAW(noist_##func)
 
+#define DEFINE_IDTENTRY_NMI		DEFINE_IDTENTRY_IST
+
 #define DECLARE_IDTENTRY_MCE		DECLARE_IDTENTRY_IST
 #define DEFINE_IDTENTRY_MCE		DEFINE_IDTENTRY_IST
 #define DEFINE_IDTENTRY_MCE_USER	DEFINE_IDTENTRY_NOIST
@@ -421,6 +423,8 @@ __visible __entry_text void ist_##func(struct pt_regs *regs)		\
 
 #else	/* CONFIG_X86_64 */
 
+#define DEFINE_IDTENTRY_NMI		DEFINE_IDTENTRY_RAW
+
 /**
  * DECLARE_IDTENTRY_DF - Declare functions for double fault 32bit variant
  * @vector:	Vector number (ignored for C)
@@ -452,7 +456,6 @@ __visible noinstr void func(struct pt_regs *regs,			\
 
 /* C-Code mapping */
 #define DECLARE_IDTENTRY_NMI		DECLARE_IDTENTRY_RAW
-#define DEFINE_IDTENTRY_NMI		DEFINE_IDTENTRY_RAW
 
 #else /* !__ASSEMBLY__ */
 
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 8ac45801ba8b..28815c2e6cb2 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -51,6 +51,7 @@ KCOV_INSTRUMENT		:= n
 CFLAGS_head$(BITS).o	+= -fno-stack-protector
 CFLAGS_cc_platform.o	+= -fno-stack-protector
 CFLAGS_traps.o		+= -fno-stack-protector
+CFLAGS_nmi.o		+= -fno-stack-protector
 
 CFLAGS_irq.o := -I $(srctree)/$(src)/../include/asm/trace
 
-- 
2.19.1.6.gb485710b